Epoxy fixturing

ABSTRACT

A system, means, and method for concurrently producing a plurality of different and irregular subcombinations by molding the subcombinations an an epoxy resin and numerical control machine processing the subcombinations.

United States Patent 1 Rehberger et a1.

[ EPOXY FIXTURING [75] Inventors: Louis W. Rehberger, Baltimore, Md.; John C. Williams, Reston, Va.; John P. Demme, Joppatowne, Md.

[73] Assignee: The United States of America as represented by the Secretary of the 7 Army [22] Filed: July 1,1970

[21] Appl. No.: 51,460

[ Feb. 13, 1973 3,200,921 8/1965 Hollis ..408/3 X 3,293,442 12/ 1966 Marantette et a1. ..408/ 3 X OTHER PUBLICATIONS Radl. R. M. Plastic Tooling for the Job Shop in The Tool Manufacturing Engineer, pp. 91-93, Jan. 1961.

Primary Examiner-Andrew R. J uhasz Assistant ExaminerZ. R. Bilinsky Attorney-Harry M. Saragovitz, Edward J. Kelly, Herbert Berl and Bernard J. Ohlendorf 52 U.S. Cl. ..408/3, 408/87, 269/7 ABSTRACT [51] Int. Cl. ..B23b 39/08 A system, means, and method for concurrently [58] Field of Search ..408/3, 87, 72, 269/7 producing a plurality of different and irregular 5 Refer no Cited combinations by molding the subcombinations an an 8 es epoxy resin and numerical control machine processing UNITED STATES PATENTS the subcombinations- 2,180,872 11/1939 Ford .f. ..269/7 X 2 Claims, 5 Drawing Figures El 2g 0 4 W 0 so H 1F 0 1*, g 1 1 PATENTED 5 3,716,303

INVENTORS Lou/s W'Rehberger John C. Williams John P. Demme ,a

. EPOXY FIXTURING DEDICATORY CLAUSE The invention described herein may be manufactured, used, and licensed by or for the Government for governmental purposes without the payment to us of any royalty thereon.

Our invention relates to a system, means, and method for concurrently producing a plurality of subcombinations, each subcombination being different from the other subcombinations and irregular.

No prior art is known disclosing any means or methodology for concurrently producing a plurality of subcombinations, each subcombination being different from the other subcombinations and irregular, and our invention was conceived and reduced to practice to overcome the concurrent production problem and to satisfy the long felt need for a means and metholodogy to concurrently produce a plurality of subcombinations, each subcombination being different from the other subcombinations and irregular.

Our invention has utility in any numerical control system or process producing an item having a plurality of different and irregularly shaped subcombinations.

The principal object of our invention is to provide a reliable and effective system and method to concurrently produce a plurality of different and irregularly shaped subcombinations.

Another object of our invention is to provide a reliable and effective system and method to economically produce a plurality of different and irregularly shaped subcombinations which reduces storage problems regarding completed subcombinations.

Other objects of our invention will be obvious or will appear from the specification hereinafter set forth.

FIG. 1 is a view showing a plurality of subcombinations in the fixture of our invention having X and Y coordinate measurements established by a digital readout coordinate measuring machine.

FIG. 2 is a view showing a numerical control drilling machine superimposed over the fixture of our invention to produce subcombinations having drilled holes at proper locations, the drilling machine having been programmed by the means shown in FIG. 1.

FIG. 3 is a view showing a plurality of different and irregularly shaped subcombinations to be drilled as shown in FIG. 2.

FIG. 4 is a view of the fixture of our invention showing cavities and raised surfaces in a cured resin to insert therein the plurality of subcombinations shown in FIG. 3 for drilling as shown in FIG. 2.

FIG. 5 is a view of the pour box of our invention prior to the pouring of resin therein which results in the fixture shown in FIG. 4.

Our invention, as shown in FIGS. 1 to 5, will now be described in detail as follows.

Any epoxy resin having a Rockwell hardness of M101, thermal expansion of 2.5/inches C. X compressive strength of 18000 to 25000 pounds per square inch, curing shrinkage of 0.0005 inch to 0.001 inch, viscosity of 8000 to 15000 centipoises at 21 C., and set-up time of 6 to 12 hours is mixed in a conventional paint shaker to a homogenous state and poured into pour box 1, shown in FIG. 5, with master subcombinations 2 and 6, as shown in FIG. 3, located in a predetermined position within the pour box prior to pouring of resin therein in the conventional molding technique manner. Pour box 1 is made of any convenient material, such as Plexiglas, and is made to predetermined dimensions to suit a given application. All undercuts on subcombinations 2 are filled with conventional modeling clay and subcombinations 2 are coated with a conventional mold release composition prior to placing subcombinations 2 in pour box 1 preparatory to pouring the resin therein; the modeling clay filling and mold release composition being utilized to facilitate easy removal after the resin has set. Pour box 1 is provided with ribs 3 arranged at predetermined height and location to suit a given molding application and to hold each subcombination 2 at the proper level; ribs 3 being fixedly mounted within pour box 1 in any conventional manner, such as by being glued. The resin is poured into the box up to subcombinations 2 and 6 center-line which lies in a plane parallel to the bottom of pour box 1, and the resin is allowed to cure at room temperature overnight. When the resin is completely hardened, master subcombinations 2 and 6 are lifted out of cured resin 4 which leaves a network of deep cavities 5 and shallow cavities 9 and raised surfaces 8 to form a fixture for insertion of subcombinations having the same geometry to be held by the cavities and raised surfaces for numerical control machine processing. If a subcombination has an irregular geometric configuration, such as subcombination 6, which prevents deeply imbedding the subcombination in the resin due to the difficulty in removing such a subcombination after the resin has hardened, a thixotropic epoxy resin is employed to positively position such a subcombination for numerical control machine processing. The resin can be any thixotropic epoxy resin having a Rockwell hardness of M85, thermal expansion of 2.0 inches/ C. X 10*, compressive strength of 17000 to 20000 pounds per square inch, curing shrinkage of 0.0005 inch to 0.001 inch, viscosity of centipoises at 21 C., and set-up time of one-half hour to 2 hours. To employ the thixotropic epoxy resin, the underside of irregular subcombinations 6 are coated with the aforementioned conventional mold release composition and the thixotropic epoxy resin placed in concave undersides of subcombinations 6, as shown in FIG. 3, and subcombinations 6 placed in pour box 1 and the molding technique carried out as above described; the use of the thixotropic resin resulting in raised surfaces 8 in FIG. 4. After curing as previously described, the thixotropic epoxy resin has bonded to cured resin 4 to form raised surfaces 8, as shown in FIG. 4, the edges of subcombinations 6 forming shallow cavities 9 similar to cavities 5. The combination of surfaces 8 and cavities 9 serving to positively position subcombinations 6 in the same fashion that cavities 5 positively position subcombinations 2 for numerical control machine processing. After the fixture shown at 10 in FIG. 4 is formed as described above, the various subcombinations are fixed in position within fixture 10 by their respective cavities 5 and 9 and raised surfaces 8 preparatory to programming, as shown in FIG. 1. The various combinations may be clamped in position within fixture 10 to hold down the subcombinations during numerical control machine processing, if desired.

To program the fixture with the subcombinations located therein, the conventional digital readout coordinate measuring technique is utilized as shown in FIG. 1. Briefly the coordinate measuring technique encompasses defining locations in the subcombinations to be machine processed, such as locating holes 11 for drilling machine processing, by probe 12, and recording the locations on a conventional computer program, not shown in the drawing, in the conventional manner; the recordation being that shown on digital readout display 13. The developed program is then fed in the conventional manner into a predetermined machine tool, such as drilling machine 7, as shown in FIG. 2, for conventional numerical control machine processing. While we have described a drilling machine application herein, our invention is applicable to any other numerical control machine process within the skill of the art.

It is obvious that other modifications can be made of our invention, and we desire to be limited only by the scope of the appended claims.

We claim:

1. A system for concurrently producing a plurality of different and irregular subcombinations comprising a cured epoxy resin mold fixture having the different and irregular subcombinations removably and concurrently mounted therein; a digital readout coordinate measuring machine to locate points on the subcombinations mounted within the mold fixture for computer program program preparation and a numerical control machine tool to accept the computer program to machine process the subcombinations; said system having a network formed in the surface of the epoxy resin to positively locate the subcombinations in the mold fixture for numerical control machine processing, said network comprising a plurality of deep cavities, a plurality of shallow cavities, and a plurality of raised surfaces integral with the epoxy resin surface and in juxtaposition to the shallow cavities; the raised surfaces being a thixotropic resin having a Rockwell hardness of M85, a thermal expansion of 2.0 inchesl C. X 10- and a viscosity of I00 centipoises at 21 C.; said epoxy resin having a Rockwell hardness of M 101 a thermal expansion of 2.5 inches/ C., and a viscosity of 8,000 to 15,000 centipoises at 21 C.

2. The system of claim 1 wherein the numerical control machine is a drilling machine. 

1. A system for concurrently producing a plurality of different and irregular subcombinations comprising a cured epoxy resin mold fixture having the different and irregular subcombinations removably and concurrently mounted therein; a digital readout coordinate measuring machine to locate points on the subcombinations mounted within the mold fixture for computer program program preparation and a numerical control machine tool to accept the computer program to machine process the subcombinations; said system having a network formed in the surface of the epoxy resin to positively locate the subcombinations in the mold fixture for numerical control machine processing, said network comprising a plurality of deep cavities, a plurality of shallow cavities, and a plurality of raised surfaces integral with the epoxy resin surface and in juxtaposition to the shallow cavities; the raised surfaces being a thixotropic resin having a Rockwell hardness of M85, a thermal expansion of 2.0 inches/* C. X 10 5, and a viscosity of 100 centipoises at 21* C.; said epoxy resin having a Rockwell hardness of M101, a thermal expansion of 2.5 inches/* C., and a viscosity of 8,000 to 15,000 centipoises at 21* C. 